Absorbent articles such as disposable diapers, incontinent pads and catamenial napkins generally include an absorbent core that has a multiplicity of components so as to improve the absorption and retention characteristics of the absorbent core. Recent advances in the field of absorbent cores have developed a relatively new class of materials known as superabsorbent polymers or absorbent gelling materials (AGM's) which can be incorporated along with absorbent fibrous materials to form improved absorbent cores. Multi-component absorbent cores wherein at least one component consists solely of hydrophillic fibers and at least one component consists of a substantially uniform combination of hydrophillic fibers and particular amounts of discrete particles of absorbent gelling materials have been found to be especially efficient and effective in absorbing and containing bodily fluids.
Several difficulties are encountered in manufacturing absorbent cores having a multiplicity of components, especially wherein at least one of the components contains discrete particles of an absorbent gelling material. While such absorbent cores can be manufactured by two or more complete core-making apparatus, the costs of providing such a system is prohibitive. Accordingly, it would be advantageous to provide a single apparatus for forming fibrous webs having a multiplicity of components.
In addition, because absorbent gelling materials are generally significantly more expensive than readily available hydrophillic fiber materials (e.g. cellulose fibers), it would be advantageous to reduce the quantity of absorbent gelling material in the core by not spreading such particles throughout the entire core but by targeting them in specific areas or components of the absorbent core. However, with conventional airlaying apparatus, it is difficult to limit such particles to only one core component. Thus, it would be advantageous to provide an apparatus and method for forming an absorbent core having a multiplicity of components wherein only one of the components contains a small amount of discrete particles of an absorbent gelling material dispersed throughout the critical areas or layers rather than the entire absorbent core.
Accordingly, it is an object of the present invention to provide an apparatus for and method of forming airlaid fibrous webs having a multiplicity of components.
It is a further object of the present invention to provide an apparatus for and method of forming, from a single column of fibers, an airlaid fibrous web having a multiplicity of components, at least one of the components containing a particular amount of discrete particles of an absorbent gelling material.